Flow analysis of p-aminophenyl phosphate with a gold nanoelectrode ensemble based detector

An alkaline phosphatase (AP) immobilized gold nanoelectrode ensemble (GNEE) was fabricated by electroless deposition of Au3+ onto the nanopores (d = 50 nm) of polycarbonate membranes and modifying the surface of GNEE successively with a self-assembled monolayer (SAM) of 2-aminoethanethiol, an alkaline phosphatase (AP) layer and a porous film of poly(4-vinylpyridine-co-styrene) (PVP). Performance of the AP-GNEE was studied by monitoring the current responses from the injection of p-aminophenyl phosphate (p-APP) into a flow injection analysis (FIA) system. Optimal conditions such as concentration of AP for immobilization, pH of carrier solution, potential applied for the analysis of p-APP were studied. Calibration graph over a broad dynamic concentration range (0.1 μM to 1.0 mM) gave satisfactory linearity (R2 = 0.986) and a very low detection limit (0.1 μM) confirming the applicability and superiority of the AP-GNEE for p-APP analysis.